For many years various types of soil materials were conditioned by using large screens which were mounted in a frame disposed at a substantially steep angle such that soil materials deposited at the top end of the screen would fall to the bottom end via gravity and particulates passable through the screen would fall to the ground beneath the screen. The pile of screened soil particulates would then be shovelled up and loaded into truck vehicles for transport to the site or location where it was to be used.
It was found, however, that the processing time for this type of soil conditioning could be shortened by mounting the screen to a shaker assembly so as to effect vibration of the soil materials as they were deposited onto the screen. The vibration of the screen not only helped to pass soil particulates through the screen openings but it also facilitated the break-up of larger chunks of material such that more of it was effectively conditioned than was heretofore possible with the non-vibrating screen apparatus. These types of soil conditioning apparatus, however, were conventionally large and heavily-built structures which were not moved very often as to do so was a costly proposition.
More recently, the industry has recognized the need for a more portable soil conditioning apparatus and one such device is manufactured by the Read Corporation of Middleboro, Mass. The apparatus is known by the tradename "SCREEN-ALL" and it comprises a shaker-mounted screen which is carried on a wheeled framework such that it may be towed behind a vehicle in the manner of a trailer. Once at the site where it is to be used, the apparatus is set up in a substantially stationary position and soil materials are deposited onto a vibrating screen from one side of the apparatus while the tailings of material are collected off of the opposite side. The conditioned soil is collected on the ground beneath the screen where it may be shovelled up and loaded into a truck for transport to the site or location where it is to be used.
There are some obvious disadvantages found in these prior art devices. Firstly, both the stationary screen and the towed shaker screen apparatus may only be loaded from a single side while soil tailings are deposited in front or at an opposite side of the respective apparatus. In either case, the pile-up of soil tailings must be periodically removed such that soil conditioning may be continued. In addition, the conditioned soil is deposited on the ground beneath the screen where it must be shovelled up and loaded into a truck for transport to the site where it is to be used. With respect to the towed shaker screen apparatus, it is a costly apparatus because it includes a wheeled carriage so that it may be towed and it further includes all of the necessary power equipment for its operation.
It is, therefore, in accordance with one aspect of the present invention an object to provide a soil conditioning apparatus which may be mounted on the dump bed of a wheeled vehicle such that soil materials may be conditioned and deposited directly into the dump bed for immediate transport and delivery to the site where it is to be used.
According to another aspect of the invention it is an object to provide a soil conditioning apparatus which is less costly to manufacture using conventional methods and materials and which may be adapted to use the available power systems of the wheeled vehicle on which it is to be carried and used.
In accordance with still another aspect of the invention it is an object to provide a soil conditioning apparatus which may be loaded from multiple positions while tailings of soil materials are deposited off of two sides of the apparatus and such tailings may not interfere with continued soil conditioning inasmuch as the apparatus may be easily repositioned for continued operation.
According to another aspect of the present invention it is an object to provide a soil conditioning apparatus which may be adapted to carry multiple and various type of screens within a shaker screen assembly such that multiple stages of soil conditioning may be accomplished.
According to still another aspect of the invention it is an object to provide a soil conditioning apparatus which may utilize the available hydraulic system of a conventional dump truck to operate hydraulic eccentric vibrator motors, which motors effectively vibrate a shaker screen assembly to obtain properly conditioned soil.
In accordance with another aspect of the invention it is an object to provide a soil conditioning apparatus which may be adapted to operate a shaker screen assembly using electrically driven eccentric vibrator motors.
According to another aspect of the present invention it is an object to provide a soil conditioning apparatus wherein soil materials may be conditioned directly into the dump bed of a truck vehicle using the available hydraulic system and wherein the truck operator may operate both the dump bed mechanism and the shaker screen assembly of the apparatus from the truck cab location and the shaker screen vibration speed is varied by the operator using the engine accelerator of the truck.